Camshaft phasers are utilized within internal combustion (IC) engines to adjust timing of an engine valve event to modify performance, efficiency and emissions. Hydraulically actuated camshaft phasers can be configured with a rotor and stator arrangement. The rotor can be attached to a camshaft and actuated hydraulically in clockwise or counterclockwise directions relative to the stator, which is rotationally connected to a crankshaft, to achieve variable engine valve timing.
Camshaft phasers can be applied to concentric camshaft assemblies that include an inner camshaft and an outer camshaft. The inner and outer camshafts can be arranged to actuate separate groups of intake and exhaust valves and facilitate phasing of one set of valves relative to the other with the use of a camshaft phaser.